Predictive Control of Three Phase AC/DC Converters

6.3. OPERATION WITH LOW SWITCHING FREQUENCY 101
6.3 Operation with Low Switching Frequency
The same experimental investigations have been repeated with reduced switching
frequency for selected control methods: DPC-SVM, CSF-P-DPC and VF-CSF-
P-DPC, under conditions listed in Tab. 6.1 and Tab. 6.3.
Control Method F sw F swAV F swMax F s T HD
per cycle [kHz] [kHz] [kHz] [%]
DPC-SVM fixed 2 2 2 4.2
CSF-P-DPC fixed 2 2 3 3.3
VF-CSF-P-DPC fixed 2 2 3 3.2
Table 6.3: Sampling and switching frequencies of tested control methods
(a) (b) DPC-SVM (c)
CSF-P-DPC
VF-CSF-P-DPC
Figure 6.11: Line current T HD factors and spectrum in DPC-SVM, CSF-P-DPC
and VF-CSF-P-DPC: (a) T HD factor measured up to 2.5 kHz, (b) harmonics
spectrum up to 2.5 kHz, (c) harmonics spectrum up to 12.5 kHz
Figure 6.12 shows steady state operation. In all cases oscillations of active and
reactive powers can be observed (Fig. 6.12 (b)), however its amplitude and period
are lower in predictive methods. It corresponds to line current T HD factor.